The goal of this study is to determine ways of reducing injection drug use and the associated injection-related HIV risk behaviors in opioid dependent injection drug users recruited during hospitalization and followed into the community. In the general hospital setting, the prevalence of injection drug use is high, patients who otherwise might not seek care are accessible, and the presence of a drug-related illness can set the stage for patients to be more receptive to interventions (Stein, 1999). Treatment of opioid dependence using pharmacologic interventions to prevent withdrawal, relieve cravings, and block or attenuate the euphoric effects of opioids has recently been enhanced with the adoption of buprenorphine/naloxone (hereafter, buprenorphine) in primary care office-based medical practices. In the proposed randomized clinical trial we will enroll 195 opioid dependent injection drug users (IDUs): A.1 PRIMARY AIMS 1) To determine if buprenorphine, initiated during hospitalization and continued after discharge, will reduce injection drug use compared to a buprenorphine detoxification condition among opioid dependent injection drug users. 2) To determine if buprenorphine, initiated during hospitalization and continued after discharge, will reduce injection-related HIV risk behaviors compared to an in-hospital buprenorphine detoxification condition among opioid dependent injection drug users. A.2. SECONDARY AIMS 1) To determine if the opioid dependent IDUs randomized to the buprenorphine continuity condition will demonstrate reduced incidence of injection-related medical conditions over the six months after hospital discharge compared to the buprenorphine detoxification condition. 2) To determine if the opioid dependent IDUs randomized to the buprenorphine continuity condition will demonstrate reduced emergency department and hospital utilization over the six months after hospital discharge compared to the buprenorphine detoxification condition. We propose that the initiation of buprenorphine therapy can and should begin during hospitalization for a population that might not otherwise seek drug abuse treatment. In addition, we propose that the linkage to maintenance buprenorphine providers after hospital discharge is feasible and important to study. The findings from this clinical trial will have immediate clinical implications for the care of medical inpatients, and will be broadly generalizable to the chronic disease management of opioid dependence across many institutions. If effective, this intervention could lead to the implementation of specific practical strategies with substantial impact on the HIV risk and drug use behaviors in a population with traditionally poor linkage to health care and an enormous burden of illness.